Energean Oil & Gas said on Tuesday it seeks to renegotiate its acquisition of Edison's upstream portfolio after its plan to immediately sell on Edison's North Sea assets to Neptune Energy fell through.

Energean is the latest in a string of oil and gas companies to seek a lower price for an acquisition agreed before the oil price collapsed by around two-thirds in the first quarter.

Private equity-backed gas producer Neptune said in March it would cut its budget for development projects by around $300 million this year and would not pay a cash dividend to its owners Carlyle and CVC Capital Partners.

In a move to expand in the eastern Mediterranean, Energean last year agreed to buy the oil and gas division of Edison for up to $850 million..

About $155 million was shaved off when Edison's Algerian assets could not be sold to Energean.

Neptune would have paid about $250 million for the North Sea assets and now has to pay Energean $5 million for cancelling the deal.

In a separate statement, Mediterranean-focussed Energean said it was in talks with Edison to amend its agreement to exclude the Norwegian subsidiary of Edison E&P from the deal.

The British assets include a 25% stake in the Glengorm gas field.

(Reporting by Shanima A in Bengaluru and Shadia Nasralla in London; editing by Devika Syamnath and Jason Neely)